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Uña de Gato

Family Malpighiaceae

Uncaria tomentosa and U. guianensis


Common Names

cat’s claw, uña de gato, paraguayo, garabato, garbato casha, samento, toroñ, tambor huasca, uña huasca, uña de gavilan, hawk’s claw, saventaro

Botanical Synonyms

Uncaria surinamensis, Nauclea aculeata, N. tomentosa, Ourouparia tomentosa
Plant parts utilized

bark, root, leaves

Documented Properties & Actions

Analgesic, anti-inflammatory, antimutagenic, antioxidant, antiproliferative, antitumorous, antiviral, cytoprotective, cytostatic, cytotoxic, depurative, diuretic, hypotensive, immunostimulant, immunomodulatory


Principal active biochemicals are six oxindole alkaloids and a number of others: ajmalicine, akuammigine, campesterol, catechin, chlorogenic acid, cinchonain, corynantheine, corynoxeine, daucosterol, epicatechin, harman, hirsuteine, hirsutine, iso-pteropodine, loganic acid, lyaloside, mitraphylline, oleanolic acid, palmitoleic acid, procyanidins, pteropodine quinovic acid glycosides, rhynchophylline, rutin, sitosterols, speciophylline, stigmasterol, strictosidines, uncarine A-F, and vaccenic.

The oxindole alkaloids significantly enhance the ability of white blood cells to attack, engulf, and digest harmful microbes or foreign bodies.


Uña de Gato,”cat’s claw”, is a thorny liana vine reputed to be a remarkably powerful immune system booster and effective in treating a wide array of maladies including cancer, systemic candidiasis, genital herpes, and AIDS (SIDA).

Uña de Gato also has anti-tumor, anti-inflammatory, and anti-oxidant properties. It has proven useful in treating arthritis, bursitis, allergies and numerous bowel and intestinal disorders. Anecdotal evidence indicates effectiveness in relieving side effects of chemotherapy.

Wild populations of this woody vine are threatened in some areas by harvesters who dig out the root out rather than simply cutting the vine and allowing regrowth. This is a foolish practice since new growth occurs rapidly when Uña de Gato vine is cut.  It grows prolifically under cultivation.

Uncaria tomentosa, reputedly the most effective of several uña de gato species, is endemic to the Peruvian Amazon and is gaining international attention for its documented curative qualities.


Cat’s claw is a large, woody vine that derives its name from hook-like thorns that grow along the vine that resemble the claws of a cat. Two closely-related species of Uncaria are used almost interchangeably in the rainforests: U. tomentosa and U. guianensis. Both species can reach over 30 m high into the canopy; however, U. tomentosa has small, yellowish-white flowers, while U. guianensis has reddish-orange flowers and thorns that are more curved. Cat’s claw is indigenous to the Amazon rainforest and other tropical areas of South and Central America, including Peru, Colombia, Ecuador, Guyana, Trinidad, Venezuela, Suriname, Costa Rica, Guatemala, and Panama. There are other species of plants with a common name of cat’s claw (or uña de gato) in Mexico and Latin America; however, they derive from an entirely different plant–not belonging to the Uncaria genus, or even the Rubiaceae family. Several of the Mexican uña de gato varieties have toxic properties.

Both South American Uncaria species are used by the indigenous peoples of the Amazon rainforest in very similar ways and have long histories of use. Cat’s claw (U. tomentosa) has been used medicinally by the Aguaruna, Asháninka, Cashibo, Conibo, and Shipibo tribes of Peru for at least 2,000 years. The Asháninka Indian tribe in central Peru has the longest recorded history of use of the plant. They are also the largest commercial source of cat’s claw from Peru today. The Asháninka use cat’s claw to treat asthma and inflammations of the urinary tract; to recover from childbirth; as a kidney cleanser; to cure deep wounds; for arthritis, rheumatism, and bone pain; to control inflammation and gastric ulcers; and for cancer. Indigenous tribes in Piura use cat’s claw to treat tumors, inflammations, rheumatism, and gastric ulcers. Indian tribes in Colombia use the vine to treat gonorrhea and dysentery. Other Peruvian indigenous tribes use cat’s claw to treat diabetes, urinary tract cancer in women, hemorrhages, menstrual irregularity, cirrhosis, fevers, abscesses, gastritis, rheumatism, inflammations; for internal cleansing and tumors; and to “normalize the body.” Reportedly, cat’s claw has also been used as a contraceptive by several different tribes of Peru (but only in excessive dosages). Dr. Fernando Cabieses, M.D., a noted authority on Peruvian medicinal plants, explains in his book that the Asháninka boil 5 to 6 kilograms (about 12 pounds! of the root in water until it is reduced to little more than 1 cup. This decoction is then taken 1 cup daily during the period of menstruation for three consecutive months, which supposedly causes sterility for three to four years.

With so many documented uses of this important rainforest plant, it is not surprising that it came to the attention of Western researchers and scientists. Studies began in the early 1970s when Klaus Keplinger, a journalist and self-taught ethnologist from Innnsbruck, Austria, organized the first definitive work on cat’s claw. Keplinger’s work in the 1970s and 1980s led to several extracts of cat’s claw being sold in Austria and Germany as herbal drugs, as well as the filing of four U.S. patents describing extraction procedures for a group of chemicals called oxindole alkaloids, and the immunostimulating actions of these alkaloids, found in cat’s claw. These novel oxindole alkaloids fueled worldwide interest in the medicinal properties of this valuable vine of the rainforest. Other independent researchers in Spain, France, Japan, Germany and Peru followed Keplinger–many of whom confirmed his research on the immunostimulating alkaloids in the vine and root. Many of these studies published from the late 1970s to early 1990s indicated that the whole oxindole alkaloid fraction, whole vine bark and/or root bark extracts, or six individually-tested oxindole alkaloids increased immune function by up to 50% in relatively small amounts. Independent Canadian researchers at the University of Ottawa documented that a whole vine extract demonstrated a strong immunostimulant effect in 1999. Independent Peruvian researchers demonstrated that a whole extract of the vine increased immune function in rats at a dosage of 400 mg/kg in a 1998 study. New, proprietary extracts of cat’s claw have been manufactured from 1999 to present day, and clinical studies have been published (funded by the manufacturers of these extracts) showing that these cat’s claw products continue to provide the same immune stimulating benefits as has been documented for almost 20 years.

But then matters surrounding cat’s claw muddied, as happens with market-driven research. A manufacturer of a cat’s claw extract funded a study around these immune-stimulating alkaloids. Their research indicated that, supposedly, two different types of cat’s claw (chemotypes) are growing in the rainforest, and/or that cat’s claw produces “good alkaloids” and “bad alkaloids.” It has coined the “good ones” pentacyclic (POA) and the “bad ones” tetracyclic (TOA) oxindole alkaloids. Its research attempts to prove that one set of “bad” alkaloids counteracts the immune benefits of the “good” alkaloids. Presumably, the presence of as little as 1% TOA content in a cat’s claw formulation would diminish the immunostimulant effect of the formulation by as much as 30%. This research has not been confirmed by independent researchers (that is, those who are not selling cat’s claw or being paid by companies selling cat’s claw). It would seek to discount or disprove all the definitive, independent research done over decades in Japan, Peru, Germany, Spain, and the U.S. (including the four U.S. patents filed by these same researchers). Much of the previous independent research was performed on whole oxindole extracts and whole root or vine extracts. This research documented the presence of both types of alkaloids in their analyses and extracts–all of which showed immune stimulant actions. Indeed, some of the “new research” refuted the marketer’s original (and confirmed) findings! As for the possibility of a “new chemotype”: a plant doesn’t change its chemical constituency in five years. Again, two species of cat’s claw exist–U. tomentosa and U. guianensis–with a similar phytochemical makeup but a different ratio of oxindole alkaloids. Admittedly (in the last 5-8 years), the presence of U. tomentosa has declined in the Peruvian rainforest by overharvesting. The lower-growing and easier to find guianensis variety is a common “adulterant” in many large lots of cat’s claw bulk material being exported out of South America today. For more technical information on the POA/TOA controversy click here.

Cat’s claw has been used in Peru and Europe since the early 1990s as an adjunctive treatment for cancer and AIDS, as well as other diseases that target the immunological system. In addition to its immunostimulating activity, other in vitro anticancerous properties have been documented for these alkaloids and other constituents in cat’s claw. Five of the oxindole alkaloids have been clinically documented with in vitro antileukemic properties, and various root and bark extracts have demonstrated antitumorous and antimutagenic properties. Italian researchers reported in a 2001 in vitro study that cat’s claw directly inhibited the growth of a human breast cancer cell line by 90%, while another research group reported that it inhibited the binding of estrogens in human breast cancer cells in vitro. Swedish researchers documented it inhibited the growth of lymphoma and leukemia cells in vitro in 1998. Early reports on Keplinger’s observatory trials with cancer patients taking cat’s claw in conjunction with such traditional cancer therapies as chemotherapy and radiation reported fewer side effects to the traditional therapies (such as hair loss, weight loss, nausea, secondary infections, and skin problems). Subsequent researchers have shown how these effects might be possible: they have reported that cat’s claw can aid in DNA cellular repair and prevent cells from mutating; it also can help prevent the loss of white blood cells and immune damage caused by many chemotherapy drugs (a common side effect called leukopenia).

Another significant area of study has focused on cat’s claw’s anti-inflammatory properties. While plant sterols (beta-sitosterol, stigmasterol, and campesterol) and antioxidant chemicals (catechins and procyanidins) found in cat’s claw account for some of these properties, new and novel phytochemicals called quinovic acid glycosides (found in the bark and roots) were documented to be the most potent anti-inflammatory constituents of the plant (in 1991). This study and subsequent ones indicated that cat’s claw (and, especially, its glycosides) could inhibit inflammation from 46% and up to 89% in various in vivo and in vitro tests. The results of these studies validated its long history of indigenous use for arthritis and rheumatism, as well as for other types of inflammatory stomach and bowel disorders. It was also clinically shown to be effective against stomach ulcers in an in vivo rat study. Research in Argentina reports that cat’s claw is an effective antioxidant; other researchers in 2000 concluded that it is an antioxidant as well as a remarkably potent inhibitor of TNFalpha production. (TNF, or tumor necrosis factor, represents a model for tumor growth driven by an inflammatory cytokine.) Their research reported that the primary mechanism for cat’s claw’s anti-inflammatory action appears to be immunomodulation through the suppression of this cytokine. Researchers in the U.S. notably reported in 2002 that the anti-inflammatory actions of cat’s claw are not attributable to immunostimulating alkaloids. This would explain why a product comprised of mostly alkaloids showed only modest benefit to arthritis patients by another group studying (and selling) a special alkaloid preparation of cat’s claw.

This same group of anti-inflammatory glycoside chemicals also demonstrated in vitro antiviral properties in another earlier study. In addition to the immunostimulant alkaloids, cat’s claw contains the alkaloids rhynchophylline, hirsutine, and mitraphylline, which have demonstrated hypotensive and vasodilating properties. Rhynchophylline also has shown to inhibit platelet aggregation and thrombosis. It may also prevent blood clots in blood vessels and relax the blood vessels of endothelial cells, dilate peripheral blood vessels, lower the heart rate, and lower blood cholesterol. Some of the newer research indicates that cat’s claw might be helpful to people with Alzheimer’s disease which could be attributable to the antioxidant effects already confirmed or, possibly, the dilation of peripheral blood vessels in the brain by alkaloids such as rhynchophylline.

In herbal medicine today, cat’s claw is employed around the world for many different conditions including immune disorders, gastritis, ulcers, cancer, arthritis, rheumatism, rheumatic disorders, neuralgias, chronic inflammation of all kinds, and such viral diseases as herpes zoster (shingles). Dr. Brent Davis, D.C., refers to cat’s claw as the “opener of the way” for its ability to cleanse the entire intestinal tract and its effectiveness in treating stomach and bowel disorders (such as Crohn’s disease, leaky bowel syndrome, ulcers, gastritis, diverticulitis, and other inflammatory conditions of the bowel, stomach, and intestines). Dr. Julian Whitaker, M.D., reports using cat’s claw for its immune-stimulating effects, for cancer, to help prevent strokes and heart attacks, to reduce blood clots, and for diverticulitis and irritable bowel syndrome.

The most common forms used today are cat’s claw capsules and tablets, which have become widely available in most health food stores at reasonable prices. There are also newer (and more expensive) proprietary extracts of cat’s claw in tablets and capsules–some backed by research (albeit paid-for research). A good-quality, natural cat’s claw vine bark with naturally-occurring chemicals is the best value, money-wise. It contains all the natural chemicals that nature provides in the proper ratio (including immune stimulating alkaloids, anti-inflammatory sterols and antioxidant glycosides) without laboratory adulteration. These invasive techniques may only extract one particular type of chemical, or change the complex ratio of naturally-occurring chemicals in herbal systems–which ignores the time-honored indigenous efficiency and synergy of the plant.

As the market demand has increased for this rainforest plant over the last five years, more companies have gone into the business of harvesting it and the quality of the bulk materials coming in from South America can be sometimes questionable.

Oftentimes, a combination of both U. tomentosa and U. guianensis are harvested and sold as “cat’s claw” (as, presently, the guianensis species is found more easily). Pick a good quality and trusted label and manufacturer for the best results and the best value.

Traditional Remedies

For general immune and health nbenefits, practitioners usually recommend 500 mg to 1 g daily of vine powder in tablets or capsules. Therapeutic dosages of cat’s claw can be as high as 10 g daily. Generally, as a natural aid for arthritis, bowel, and digestive problems 3-5 g daily is recommended if a good product is obtained. Alternatively, a standard vine bark decoction can be used as well much the same way in indigenous people of the Amazon use it. Dosages for a standard decoction for general health and maintenance is 1/2-1 cup of a decoction once daily and up to 1 cup three times daily in times of special needs. Adding lemon juice or vinegar to the decoction when boiling will help extract more alkaloids and less tannins from the bark. For more information on preparing decoctions, click here. Use about 1/2 teaspoon of lemon juice or vinegar per cup of water. For standardized and/or proprietary extract products, follow the label instructions.


Cat’s claw has been clinically documented with immunostimulant effects and is contraindicated before or following any organ or bone marrow transplant or skin graft.

Cat’s claw has been documented with antifertility properties and is contraindicated in persons seeking to get pregnant (this effect however has not been proven to be sufficient to be used as a contraceptive and should not be relied on for such).

Cat’s claw has been documented with chemicals which can reduce platelet aggregation and thin the blood. Check with your doctor first if you are taking coumadin or other blood thinning drugs and discontinue use one week to ten days prior to any major surgical procedure.

Cat’s claw requires sufficient stomach acid to help break down the tannins and alkaloids during digestion and to aid in absorption. Avoid taking bark capsules or tablets at the same time as antacids. Avoid taking high tannin (dark colored) liquid extracts directly by mouth and dilute first in water or acidic juice.


Large dosages of cat’s claw (3-4 gram dosages) have been reported to cause some abdominal pain or gastrointestinal problems including diarrhea (due to the tannin content of the vine bark). The diarrhea or loose stools tend to be mild and go away with continued use. Discontinue use or reduce dosage if diarrhea persists longer than
3-4 days.

Drug Interactions

Due to its immunostimulant effects, cat’s claw should not be used with medications intended to suppress the immune system, such as cyclosporin or other medications prescribed following an organ transplant. (This theory has not been proven scientifically.)

Based upon in vivo rat studies, cat’s claw may protect against gastrointestinal damage associated with nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.

May potentiate coumadin and blood-thinning drugs.



Abscesses, AIDS, arthritis, anti-inflammatory, asthma, blood cleanser, “bone pains,” cancer, cicatrizant, cirrhosis, contra-ceptive, cytostatic, diabetes, diarrhea, disease prevention, dysentery, fevers, gastric ulcers, gastritis, gonorrhea, hemorrhages, herpes, immune disorders, inflammations, intestinal affections, kidney cleanser, menstrual irregularity, prostatitis, rheumatism, skin disorders, stomach, ulcers, urinary tract disorders, tumors, wounds


Dysentery, gonorrhea


Dysentery, intestinal affections, wounds

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